Treatment of spent cannabis biomass with activating agent

Abstract

A process to transform spent cannabis biomass into activated carbon via a treatment involving a chemical activation process. The spent cannabis biomass is mixed with an activating agent and then subjected to a heat treatment. The spent cannabis biomass is heated in stages, the first to remove water and volatile components, and the second to reclaim leftover cannabinoids. During a third, higher temperature stage, the biomass is converted to activated carbon.

The invention claimed is: 
     
       1. A process for treating spent  cannabis  biomass comprising:
 mixing spent  cannabis  biomass with an activating agent to result in an impregnated spent  cannabis  biomass; 
 raising the impregnated spent  cannabis  biomass to a first temperature that is sufficient to remove water and volatile components from the impregnated spent  cannabis  biomass; 
 raising the impregnated spent  cannabis  biomass to a second temperature that is sufficient to recover cannabinoids from the impregnated spent  cannabis  biomass, wherein the second temperature is higher than the first temperature; 
 collecting the recovered cannabinoids by directing them into chilled ethanol: 
 raising to a third temperature the impregnated spent  cannabis  biomass, wherein the third temperature is higher than the second temperature; and 
 maintaining the impregnated spent  cannabis  biomass at the third temperature until the impregnated spent  cannabis  biomass has been transformed into activated carbon. 
 
     
     
       2. The process of  claim 1 , wherein:
 the activating agent is KOH, H 3 PO 4  or ZnCl 2 ; and 
 the spent  cannabis  biomass is mixed with the activating agent at a ratio of between 1:0.5 and 1:3 by weight. 
 
     
     
       3. The process of  claim 1 , wherein the activating agent is mixed with the spent  cannabis  biomass for 2 to 24 hours. 
     
     
       4. The process of  claim 1 , wherein:
 the impregnated spent  cannabis  biomass is maintained at the third temperature for 0.5 to 2 hours; and 
 the third temperature is between 500 and 900° C. 
 
     
     
       5. The process of  claim 1 , wherein the first temperature is 100±20° C. and the second temperature is 170-500° C. 
     
     
       6. The process of  claim 5 , wherein the first temperature is 100° C. and the second temperature is 500° C. 
     
     
       7. The process of  claim 1 , wherein the impregnated spent  cannabis  biomass is heated in a fixed bed reactor that has an exhaust line with a bypassable cold trap, the process comprising purging the fixed bed reactor with nitrogen before heating the impregnated spent  cannabis  biomass. 
     
     
       8. The process of  claim 7 , comprising, while raising the impregnated spent  cannabis  biomass to the first temperature, directing vapor evaporated from the impregnated spent  cannabis  biomass to bypass the cold trap. 
     
     
       9. The process of  claim 8 , comprising, while raising the impregnated spent  cannabis  biomass from the first temperature to the second temperature, passing vapor evaporated from the impregnated spent  cannabis  biomass through the cold trap. 
     
     
       10. The process of  claim 1 , comprising maintaining the impregnated spent  cannabis  biomass at the first temperature until all the water is removed from the impregnated spent  cannabis  biomass. 
     
     
       11. The process of  claim 1 , comprising collecting water and volatile components from the impregnated spent  cannabis  biomass using a cold trap, while the impregnated spent  cannabis  biomass is below and at the first temperature. 
     
     
       12. The process of  claim 1 , comprising maintaining the impregnated spent  cannabis  biomass at the second temperature until all the cannabinoids have been recovered from the impregnated spent  cannabis  biomass. 
     
     
       13. The process of  claim 1 , comprising maintaining the impregnated spent  cannabis  biomass at the third temperature for 1 hour. 
     
     
       14. The process of  claim 1 , comprising passing nitrogen gas over the impregnated spent  cannabis  biomass throughout the process. 
     
     
       15. The process of  claim 1 , comprising milling the spent  cannabis  biomass to an average particle size below 2 mm prior to mixing the spent  cannabis  biomass with the activating agent. 
     
     
       16. The process of  claim 1 , comprising washing the activated carbon with hot deionized water when the activating agent is acidic. 
     
     
       17. The process of  claim 1 , comprising washing the activated carbon with a diluted HCl solution and then washing the activated carbon with deionized water, when the activating agent is alkaline. 
     
     
       18. The process of  claim 1 , wherein the chilled ethanol is at a temperature between 0° C. and −40° C.